1. Field of the Invention
This invention relates to the field of mixing liquids to form a homogenous suspension or solution. More particularly, this invention further relates to the field of mixing liquids containing particulate material in order to obtain a homogeneous suspension of particulate material in the liquid.
2. Discussion of the Art
Automated instrumentation has been developed for performing assays in clinical laboratories. Automated instrumentation has been used in the area of immunoassays. In the area of immunoassays, certain reagents known as solid-phase reagents are used in heterogeneous immunoassays. In heterogeneous immunoassays, the solid-phase reagent can include paramagnetic particles, while another reagent, the labeled reagent, can include a chemiluminescent label. In order to obtain accurate and precise assays results, the solid-phase reagent must exist as a uniform, homogeneous dispersion as particles in a dispersing medium. One problem encountered when using solid-phase reagents is that over a period of time, the particulate material in the reagent tends to settle out of the dispersion. Therefore, there is a need to re-disperse the particulate material of the solid-phase reagent in the dispersing medium. In an automated system, the solid-phase reagent must be re-dispersed by the apparatus, without manual shaking by an operator. Many references in the prior art indicate apparatus and methods for maintaining solid particulate material in a uniform, homogeneous dispersion.
U.S. Pat. No. 5,104,807 describes an apparatus in which a train of containers is provided on a movable holder. The train is conveyed such that it passes through a container rotating area and a container non-rotating area. The motion of the movable holder driven by a driving source is transmitted to the containers located in the container rotating area as a rotational force of the containers on their own axes. In the container non-rotating area, a light beam of a photometer is formed so that light measurement can be performed to measure the test solutions in the containers which arrived at the non-rotating area.
U.S. Pat. No. 3,848,796 discloses a sedimentation rate centrifuge comprising a centrifuge head, a driven shaft mounting the head for rotation therewith and a drive motor coupled to the driven shaft for imparting rotative motion thereto about the axis of the each in intermittent periods of predetermined duration to generate centrifugal force applicable in a direction generally normal to its axis of rotation. The centrifuge head comprises a body, a sample tube holder carried by the body near the periphery thereof, the sample tube holder constructed and arranged to receive elongate sample tubes each containing a thin column of blood and each vertically arranged and oriented substantially parallel to the axis or rotation of the body so that the centrifugal force is applied laterally to the long axis of the sample tubes, means for causing periodic rotation of the sample tube holder and the associated sample tube about its own long axis between each application of centrifugal force and when the body is substantially at rest.
UK Patent Application GB 2 081 118 describes the simultaneous mixing of the contents in each of a plurality of containers each including a liquid. The mixing is effected by simultaneously causing the containers each to be rotated about its own axis first in one direction and then in another. In one embodiment the test tubes are mounted in a turntable with a disc-shaped drive member frictionally engaging each tube and rotatable (independently of turntable) to cause each tube to be rotated about its own axis to mix the contents therein. The turntable assembly is particularly suitable for use with automated analysis machines.
U.S. Pat. No. 6,436,349 describes a reagent transport apparatus for use on a clinical analyzer. The reagent transport apparatus comprises a base, a reagent tray mounted on the base for rotation about a primary vertical axis of rotation; a drive motor for rotating the reagent ray about the primary vertical axis of rotation; a control unit in the form of a computer circuit for operating the drive motor to selectively position a selected one of the reagent containers at the reagent aspiration point; a plurality of mounting assemblies disposed in a first circle on the reagent ray, concentric with the primary vertical axis of rotation; a plurality of agitating assemblies disposed in a second circle on the reagent ray, concentric with the primary vertical axis of rotation, each of the agitating assemblies having a respective secondary vertical axis of rotation; and agitating motor for rotating each of the plurality of agitating assemblies about the respective secondary vertical axis of rotation, each agitating assembly comprising a first reagent container holder mounted on the reagent tray for rotation about the respective secondary vertical axis of rotation, the reagent transport assembly further comprising a ring gear, concentric with the primary vertical axis of rotation and coupled to the agitating motor, in driving engagement with each of the satellite gears wherein rotation of the ring gear by the agitating motor about the primary vertical axis causes each of the satellite gears to rotate about the respective secondary vertical axis.